venom

venom

venom or zootoxin, any of a variety of poisonous substances produced by animals. In poisonous snakes, venom is secreted in two poison glands, one on each side of the upper jaw, and enters the fang by a duct. Snake venom is a complex substance, containing various enzymes and toxins. Venoms differ in their effect according to the preponderance in them of hemotoxic, hemolytic, or neurotoxic agents. Hemotoxins perforate the blood vessels, causing hemorrhage, and hemolysins dissolve the red blood cells. The venom of the fer-de-lance is chiefly hemotoxic; that of the rattlesnake, the copperhead, and the moccasin is both hemotoxic and hemolytic. Neurotoxins produce paralysis, often of the nerve centers that control breathing, thus causing a quicker death from suffocation. Cobras, coral snakes, scorpions, and spiders produce neurotoxic venoms. The venom of the gaboon viper is both hemotoxic and neurotoxic. Venoms may also contain agglutinins, which promote coagulation of blood, or anticoagulants, which have the opposite effect. The venoms of various snakes have been used medicinally, according to their specific properties, as painkillers (in arthritis, cancer, and leprosy), antispasmodics (in epilepsy and asthma), and blood coagulants (in hemophilia). The venom of the Russell's viper has been used as a coagulant in tonsillectomies and for bleeding gums. The effect of any snakebite necessarily depends on the quantity and kind of toxin it contains, as well as on the resistance of the victim. Immune serum against snake venom, or antivenin, can be prepared by repeatedly injecting sublethal doses of venom into an animal such as the horse. The immune serum thereby produced in the animal can be extracted and used to treat snakebite victims. Poisons are produced by animal species of every phylum; examples include the poison in the rounded warts of the skin of toads, the venoms of spiders, scorpions, bees, and other arthropods, and the poison of jellyfish and other coelenterates. See also toxin.

Venom is any of a variety of toxins used by certain types of animals, for the purpose of defense and hunting. Generally, venom is injected by such means as a bite or a sting, while a poison is absorbed by ingestion or through the skin.

Because they are tasked to defend their hives and food stores, bees synthesize and employ an acidic venom (apitoxin) to cause pain in those that they sting, whereas wasps use a chemically different venom designed to paralyze prey, so it can be stored alive in the food chambers of their young. The use of venom is much more widespread than just these examples, of course.

The difference between Venomous & Poisonous

There is a difference between organisms that are venomous and those that are poisonous, two commonly confused terms applied to plant and animal life. Venomous, as stated above, refers to animals that deliver (often, inject) venom into their prey when hunting or as a defense mechanism. Poisonous, on the other hand, describes plants or animals that are harmful when consumed or touched. A poison tends to be distributed over a large part of the body of the organism producing it, while venom is typically produced in organs specialized for the purpose. One species of bird, the hooded pitohui, although not venomous, is poisonous, secreting a neurotoxin onto its skin and feathers. The slow loris, a primate, blurs the boundary between poisonous and venomous. From patches on the inside of its elbows it secretes a toxin, which it is believed to smear on its young to prevent them from being eaten; however, it will also lick these patches, giving it a venomous bite.

Snake venom

Snake venom is produced by glands below the eye and delivered to the victim through tubular or channeled fangs. Snake poisons contain a variety of peptide toxins. Snakes use their venom principally for hunting, though the threat of being bitten serves also as a defense. Snake bites cause a variety of symptoms including pain, swelling, tissue damage, low blood pressure, convulsions, and hemorrhaging (varying by species of snake).

Doctors treat victims of a venomous bite with antivenin, which is created by dosing an animal such as a sheep, horse, goat, or rabbit with a small amount of the targeted venom. The immune system of the subject animal responds to the dose, producing antibodies to the venom's active molecule; the antibodies can then be harvested from the animal's blood and applied to treat envenomation in others. This treatment can be used effectively only a limited number of times for a given person, however, as that person will ultimately develop antibodies to neutralize the foreign animal antibodies injected into him (anti-antibody antibodies). Even if that person does not suffer a serious allergic reaction to the antivenom, his own immune system can destroy the antivenin before the antivenin can destroy the venom. Though most people never require even one treatment of antivenin in their lifetime, let alone several, people who work with snakes or other venomous animals may.

Aristolochia rugosa and Aristolochia trilobata, or "Dutchman's Pipe," are recorded in a list of plants used worldwide and in the West Indies, South and Central America against snakebites and scorpion stings. Aristolochic acid inhibits inflammation induced by immune complexes, and nonimmunological agents (carrageenan or croton oil). Aristolochic acid inhibits the activity of snake venom phospholipase (PLA2) by forming a 1:1 complex with the enzyme. Since phospholipase enzymes play a significant part in the cascade leading to the inflammatory and pain response, their inhibition could lead to relief of problems from scorpion envenomation.